var
a:string;
s:array[1..255]of char;
i,k,j,rez:integer;
begin
a:='sina';
repeat
writeln('vvedite simvol');
inc(k);
readln(s[k]);
until s[k]='!';
for i:=1 to 4 do
for j:=1 to k do
if a[i]=s[j] then
begin
inc(rez);
break;
end;
if rez=4 then writeln('yes') else writeln('no');
readln;
end.